Preparation of lignosulfonate‐based nanofiltration membranes with improved water desalination performance

• Main Authors: Wangqu Liu, Xin Geng, Saisai Li, Xia Zhan, Jiding Li, Luying Wang, Jiandu Lei
• Format: Article
• Language: English
• Published: Wiley-VCH 2021-06-01
• Series: Engineering in Life Sciences
• Subjects: layer‐by‐layer self‐assembly; nanofiltration; polyethylenimine; sodium lignosulfonate; water desalination
• Online Access: https://doi.org/10.1002/elsc.202000102
• ISSN: 1618-0240; 1618-2863

Abstract Pulping and papermaking generate large amounts of waste in the form of lignosulfonates which have limited valorized applications so far. Herein, we report a novel lignosulfonate‐based nanofiltration membrane, prepared by using polyethylenimine (PEI) and sodium lignosulfonate (SL) via a layer‐by‐layer (LbL) self‐assembly. As a low‐cost and renewable natural polyelectrolyte, SL is selected to replace the synthetic polyelectrolyte commonly used in the conventional LbL fabrication for composite membranes. The prepared LbL (PEI/SL)7 membranes were crosslinked by glutaraldehyde (GA) to obtain (PEI/SL)7‐GA membranes with compact selective layer. We characterized (PEI/SL)7 and (PEI/SL)7‐GA membranes to study the chemical compositions, morphologies, and surface hydrophilicity. To improve the nanofiltration performances of the (PEI/SL)7‐GA membranes for water desalination, we investigated the effects of the crosslinking time, GA concentration and the NaCl supporting electrolyte on membrane structure and performance. The optimized (PEI/SL)7‐GA membrane exhibited a permeating flux up to 39.6 L/(m2·h) and a rejection of 91.7% for the MgSO4 aqueous solution 2.0 g/L concentration, showing its promising potential for water desalination. This study provides a new approach to applying the underdeveloped lignin‐based biomass as green membrane materials for water treatment.